step 1. do some lessons first to see if you can stomach it, and whether you have the aptitude for it.
step 2. have a medical as mentioned before to see if you're fit to hold a licence.
step 3. contact your nearest school and do your ppl.
modular is the cheapest method, but you'll still spend £160-£220 an hour on lessons.
the ppl will set you back maybe 8 grand or more depending on the school.
and that's just the start of it.