your boiler will have a hot water flow rate off about 10 to 12 L a minute max so as long as you fit a thermostatic mixing shower or evern better a pressure balanceing shower which is designed for combi boilers all will be fine only problem will be if some one opens a hot tap while your having a shower, because if they do the flow will drop right off, but still the best one to go for mate, if i was you i whould get a Mira combiforce this is pressure balanced can be surface mounted or built in looks modern and is a very good shower but will cost over £200 but worth it. Just need to run a hot water pipe to the shower as you allready have cold.

hope this helps dunc