Does anybody know if it's legal - or if it affects house insurance -
to plumb in your own gas hob? Or does it have to be done by a Corgi
man?

The general opinion seems to be that it can be done legally by the homeowner
in many circumstances. However, there are some caveats.

1. You must be competent. This means that things like jointing pipe, leak
detection, pressure testing etc. must be understood and correctly performed
to the standards expected of a CORGI registered fitter.

2. The house must not be rented out.

3. Rules (such as whether using flexible hoses is acceptable or not) must be
followed.

4. No payment of any kind can be made.

Christian.