Having a fixed wing ppl will give you a bit more confidence in the air and the initial fears of being 'solo' won't be the same second time around. You would probably manage the ppl(h) in minimum hours, ie 10% of your fixed wing hours up to 6 hours max. You could go to many places for a trial lesson but it depends exactly where you are. As you probably already know, regular flying will help minimise the hours required to get to test standard.
If you use a rough guide of doing it in the usual minimum of 45hrs then 45 x £250 + costs =£12k. (approx) Some places will be cheaper. Cost to hire an a/c after licence issue is more expensive than fixed wing.
Good luck if you do take it up. Best way to spend money I think.