I've reported the use of the word pr**k to the moderators - it rather confirms my feelings that these forums, rather than being a source of useful advice, are the province of mindless trolls.
Actually, while there are one or two people who have a tendency towards that, on the whole this section of the board is inhabited by some knowledgable and helpful electricians (I'm not an electrician BTW). The advice they have given you is correct, but you give the impression that you have no intention of taking any notice of it. That happens quite often, for some reasons people seem to think that all there is to electrickery is connecting a few wires up and if it doesn't blow the fuse then it must be OK
J3. I can do what I did - put the wiring in myself (total cost for parts under £60) but because it might be deemed to be an 'installation' I then have to get it documented for Part P compliance at a cost of around £150.
Unfortunately you can't do that - not for £150 anyway.
An electrician cannot certify someone else's work - the only way for them to do your paperwork would be for them to cliam to have done the work themselves in which case they could self certify through their scheme (assuming they are a member of an approved scheme). For the work you've described, no-one is going to put their name to it - sorry.
You can go the Building Control route. You need to notify your Local Authority Building Control dept (LABC) before starting work and pay their fees. When you've done the work, they will inspect it and (assuming it's OK) issue a completion certificate. it seems my LABC are among the cheaper, they charge £150 for minor electrical works
if you are in a position to provide the correct test results, or £225 otherwise (which would be the case for you).
But, for the work you describe, it would not pass inspection or testing.
Sadly, all this kind of nastiness does is reinforce the general opinion that all electricians, plumbers and other tradesmen are crooks. My landlord just had a lot of work done on the property by a well-known local electrical contractor - they left lights not working, bare wires, sockets not properly installed and a load of other faults that I had to correct.
Bear in mind that your landlord sounds like the sort that give the rest of us a bad reputation - we aren't all like Rigsby ! Probably went with the cheapest bodger he could find. Doesn't mean all tradesmen are crooks. But, that's not an excuse for you to start doing your own thing - you should have reported the problems to your landlord, and if they weren't fixed, reported it to ... hmm, not sure, who do you report dangerous electrical work to ? I think any of the electricians here would rather see the sort of cowboy you appear to have been subjected to dealt with.
If I found a tenant had been interfering with the electrics, they'd be getting a section 21 notice (be out in 2 months, no reason needed). However, there would never ever be a need - assuming that the tenant actually reported any faults.
Through my work, I come across a variety of trades on site - they "vary in ability" somewhat. Some I like working with, they understand what I need* etc. Others are definitely in the "wouldn't want to work with them again" category.
* When installing networks, it's not uncommon for the electricians to pull in the cables which I then terminate - saves two lots of pulling work and they can "lid up" the dado trunking in one go.