Ted I assume that you didn't get an earlier reply as this question is goverened by many factors, not least of all, your own decision.
When you mention a 'boiler that does the lot', I assume you mean a condensing combination boiler which provides both central heating and hot water without the need for bulky tanks and cylinders.
Firstly you have to make sure that your water supply is up to the job....
and
How many people live in the property...?
How many bathrooms, shower rooms/ en suites in the property...?
Is it likely that more than one hot tap will be used at any given time...?
Combi's no matter how small or large their output can only manage one tap at a time...! Realistically...!
If on the other hand you rejig your current system, it will work aswell as it does now if not slightly better on the h/w pressure, although as with everything in life there will be issues to overcome, which a competent plumber will advise you on.
Would certainly be the cheapest option, especially if there is nothing wrong with the current boiler.
Hope this helps....