As for the camcovers... it is best done DIY (had mine done 4 years ago by the dealer under warranty, but did it again myself in April last year). There is a very good guide in the Maintenance Guides section.
Reason is that there are few pitfalls that can cause the camcovers to leak again very quickly.
1. You must use original Vx gaskets (around £25 per head). Other makes may seem the same, but they will brittle and leak very quickly.
2. You must use Vx own-brand RTV sealant, and only in the places as described in the Maintenance Guide - using any other type of sealant, or not using sealant at all, or using the right sealant but all along the gasket and not just in the right places, will all cause the gaskets to leak again very quickly.
3. The camcovers must be evenly torqued to 8NM, or they will leak again....
Problem is many independent garages don't know these things, they think it is a straightforward gasket saap, and when the customer comes back with a fresh leak a couple of weeks later, their standard response is that the camcovers are 'warped' and new ones are needed... Wapred camcovers are very rare mainly because these are plastic units, and will only occur if the engine seriously overheated for a long period of time.
So in short best thing is DIY (then you know you got it right..), then independent, but only one that comes recommended and has proven he knows how to to the job, and last Vx dealers, on balance they are more likely to get the job done right (though not always!) but this will come at a price.