11 speed chainwheel with double 8 speed group?

Many thanks. I'll try 9 speed chain and i'll get back within a couple of weeks max with a pic or 2 and let all know how it has worked out.

Thanks for additional comment. You can obviously see I don’t have a clue about bike parts to put it lightly but I appreciate all your efforts to explain different things.
So do people think I should try out this setup (Ultegra 6800 chainwheel with Micrshift R8 deraileurs and shifters, plus 8 speed Sunrace cassette) with an 11 speed chain firstly? or should I go 8 speed chain?

If it doesn’t work well, I will just revert to the original plan of fitting the unbranded Claris, since like I said previously, I just can’t justify nearly 350 more euros to complete the Ultegra full groupset.
Including frame cost, I’ve already spent about 750 euros on everything I bought so far, so it’s reached the point where the deal is certainly no good if I go higher.
Buying the Ultegra complete group would take me to 1100 for a bike that you can now buy for 999,99 with full Ultegra and slightly better wheels.
I can see that since I bought the Ultegra chainwheel, the trouble begun. Before that I’d not wrong footed in a logical plan. Little more than 600 euros total for an Ultra AF with Micrshift R8 groupset and nice unbranded Claris chainwheel, was genuinely a pretty good deal.
Yeh, it’s not the lightest aluminium frame/fork but probably lighter frame/fork than nearly any ready built bike at that sort of price point.

A last option I thought of was buying the Sensah Empire partial 11 speed groupset (shifters and deraileurs) at 139,99 euros on Amazon and pairing that with the Ultegra chainwheel, whilst selling the Microshift and Claris chainwheel to fund the purchase.
However I am weary of such a cheap groupset (yeh, Microshift is cheap too, but I know it well and like it) I don’t know of and which is hardly reviewed much at all. Sensah claims it’s above 105 level, but I find that very hard to believe!
Also seems to be a lack of clarity over whether it’s Shimano compatible. Some sites say it is, while others say it’s only Sram compatible. So I would say that puts the nail in the coffin.
Last thing I need is more incompatibile bike parts!
Want to build this damn thing and post some pics.
Cheers.

Cheers for all for the additional comments and thoughts.
I’ll probably try with the Ultegra since it fits the current press fit BB, then revert to fitting the Claris if there are problems.
Microshift claim the R8 groupset I have to be 100% Shimano compatible so I don’t see that I need to buy Claris (or any other 8 speed) deraileurs.

I just need to buy the cassette now and the chain. I’m thinking of an 8 speed cassette but what about the chain? Should I be getting an 8 speed chain for this project (of trying to use the Utegra crank)?
Thanks again.

Thank you. A pity but not a huge surprise I suppose. Cheers for the educational explanation.
I wonder now should I just revert to my original plan of fitting the unbranded Claris double 8 speed chainwheel (I got a particularly good price on the Ultegra so I think I could easily flip it on ebay without losing more than 10 euros max in all).
I actually think the FC-RS200 looks nice (smart and sleek) once you remove the plastic chainguard. It's just that it's quite a bit heavier than the Ultegra and also when I saw the Ultegra with it's large metal pipe-like central movement part vs the more octagonal style that the FC-RS200 BB (BBUN26) employs if I'm not mistaken, I got thinking to myself (whether right or wrong), 'well, that big thing probably makes the cycle better too!'.
Also I don't particularly fancy knocking out the press fit BB even if maybe it's not a hard job.

Are you saying I could keep the Microshift R8 brake/shift levers if I otherwise put full Ultegra (or Tiagra) on the bike? I believe the answer is probably no.
To be clear, this is what I have currently:

*New Ultra AF bike frame with handlebars, seatpost and saddle
*Microshift R8 double 8 speed (partial) groupset consisting of brake/shift levers and both rear and front deraileurs.
*2 direct mount brake calipers (105 rear and Ultegra front)
*2 chainwheels (Shimano FC-RS200 and Shimano Ultegra 6800)
*Shimano RS100 wheelset with tires

I would not have a problem buying 2 Ultegra deraileurs. It would only cost about 70 euros.
It's more so the Ultegra brake levers which cost about 200 euros best price which are posing as the dealbreaker.
You see I bought the frame for 200 euros and when I add up everything I have spent on top of that I am at about 700 euros by now.

The same bike in question is now sold (in end of series sale) on Decathlon with full Ultegra for 999,99 euros.
If therefore I buy the Ultegra levers along with the two Ultegra deraileurs I'm going to pretty much be up to a grand and, as valuable as the experience of building a bike is, it will make me a twit to have paid a grand for bike I could have bought already built with the same components (or in fact even better perhaps since I've got a 105 back brake and RS100 wheels which are not quite as well spec'd as the Mavic Cosmic that come on the bike at Decathlon).

Oh well, if I can't use the Microshift levers with otherwise full Ultegra (less the 105 rear brake caliper), maybe I'll just be that twit and buy the Ultegra. Tiagra might save me 50-70 euros I guess and thanks for mentioning how good it is in the present age, but I think for a saving like that I'd just take the hit and get full Ultegra.

On the other hand, it seems not only dumb, but perhaps more to the point sort of boring/unsatisying to build up this bike with plain full Ultegra, the same way the bike comes factory issued for the same price.
I was really looking forward to see that Microshift groupset on it and for it to be a unique build. I know the performance would be much worse than with Ultegra but I do quite like Microshift as a budget groupset and feel that if I can say I got the bike frame and built it myself like that all for 700 euros, then that makes a pretty nifty deal.

Well, it's only me that can decide I guess, and decide I damn will in early 2019 (lol!)with no further delay as this has dragged on far too long (A mix of constant indecision and the Microshift groupset taking an eternity to finally arrive with me, as it now has, from Taiwan).

I do think I'm edging back towards the Microshift R8 group with the Shimano 8 speed chainwheel, but I welcome and value anybody's opinions.

Thanks very much again Mylesrants. Happy holidays.