bike build, yay another one

[andy0001]

Hey all,
so i bought a bike(a merida scultura disc 200) i got it on ebay, i am a sucker for a good looking bike and like to spend a bit of time tinkering in the shed. this is the bike when fully set up.

so it has, the frame, forks, wheels, clinchers, seat post, which i threw together earlier, the reviews for this bike say the braking is not great so immediately bought a trp spyre slc set for it, i am going to be building this for commuting daily and also the ride100 and training for it. (i currently own a cheap specialized hybrid that i use to and from the station for work-3m each way-a couple of small hills which will be sold when this is built)
The original bike(listing)had shimano sora 11-28 18 speed but i'm starting with nothing but also not spend silly money on it(ebay will be a very used place) And i plan to try and keep the cost down a bit, so far it's cost under 300, i also have a seat, a bottom bracket and a set of new road bike bars to stick on her, plus have brake and gear cables, sleeving, ferrules and tape for bars and all the tools to get the job complete.
The main things to buy is derailers, gears, shifters, cassette and crankset.
trying to work out whether to go Ultegra or 105, i'll be setting a 300 ish limit to complete it and mostly second hand bits.
when the weather isn't pouring down i'll throw a few pics on here. any advice happily welcome.

 

[andy0001]

had to put this on the backburner for a couple of weeks, wanted to ask for a bit of advice
below is what the bike should have been set up with but i'm starting from scratch so have a free run at it:

rear deraileur Shimano Sora, 18 speed
shifters Shimano Sora, 18 speed
Shimano Sora levers with Promax Decode R mechanical disc brakes, 160mm rotors
asi say these are what the original bike should have had on it but mine has a bottom bracket and nothing else yet.


i have some TRP spire slc mechanical disc brakes and 160mm rotors that have come off a previous build(upgraded another bike) that are nigh on new which i was going to use.
i also have a a 10speed 11-28 cassette(previous owner said he had a 10 speed on it previously so it fits)
what i need is advice on which shifters/brakes to go for?
10 speed mech disc brakes seems to be tiagra, or is there an ultegra option that works? (don't have the crankset yet) anyone know? it seems to be hard to find exactly what to go for, i thought some of you guys might know better.
so er, help

 

[Gillstay]

Pictures would help us this end