Foot Well Replacements

Hi, I have a 1990, 110. 200tdi LHD, I have the replacement foot wells which are to be fitted. I have had a look at the job but it looks a bit too involved for me to tackle. I have an electric arc welder which I have been playing around with on other bits of metal but my skills are not very good. I think I would end up just burning a hole through them.
I have taken it round to a couple of local garages round here and there suggestion was to just cut out the rusty part and fit a plate over it. Not sure I like that idea as to my mind the rot will just come back sooner or later.
I live in France but plan on a trip to the UK very soon. Can anyone recommend a place where I could get the job carried out?
Any help or suggestions would be greatly appreciated.

What part of the UK will you visit ?

i would do as the garages suggest mate! As a new footwell is bit excessive for something that will rust again no doubt. Cut rust out - weld in new plate - seal with waxoil and underseal

UK visit is flexible. Arrive Dover, Then Portsmouth, Southampton, Bournemouth. Weybridge then up to York.