Hi Charlie,
As you can see, you'll get as many answers as there are people.
Still, I'll try and tell you as much as I know, and as has been said before, you can get the details elsewhere.
A PPL in the UK, on an R22, assuming you do it in close to the minimum number of hours, will cost you about £12,000. It's far cheaper to do it in the US, Australia, or South Africa. However, you'll either need to do a JAR PPL, at a school which does these, or sort out converting what you get if you want to fly afterwards in the UK...and that last bit I don't know about. Other disadvantages are different radio terminology, not being used to UK weather, different charts etc. Most people who get a US PPL need a few hours extra training when they get back to the UK. You should save money overall though.
Short sight...not a problem for a Class 2 medical for private flying. If you want to go commercial you'll need a Class 1, and won't get it if your eyesight is outside certain limits, which I'm not sure of. You could do a search on the medical forum to find out. However, if you're serious about getting a CPL, it's worth getting a Class 1 early on, just to make sure that you can. Again, rules are different in other countries.
If you want a CPL you need 155 flying hours in total, and to do 14 ground exams. You then do a 30 hour flying course, with a test at the end of it. What does that qualify you for? Very very little, with the industry as it is now. There's loads of low hours CPLs around who'd love the sort of work you mention, and the chance of getting it is virtually nil.
If you want to know anything else along these lines, have a look back at old posts on here...do a search. Most of this stuff his been covered in quite a lot of detail.