<human>: Can you give me a shortened version of the text?

Hey Personal Finance guys and girls!
 
Long time lurker but just made an account to get some advice on a sticky situation I may have gotten myself into.

I've just started my first job in the UK out of uni working for a guy who I'd previously worked with during a summer job a few years ago. 
The job is great and fun and I want to stay. However, when I began, my boss told me he couldn't put me on PAYE straight away (the first 4 months) and to invoice him saying that because it's for such a short time I won't have to pay tax on it (I'm invoicing £1500/month btw).
I've now been doing this for four months, and am just about to move onto PAYE, being paid extra to make up for the amount I'll lose now I'll be paying tax on it.

I'm just wondering how likely this is to come back and bite me in the arse, and if there's anything I can do to mitigate the problem. My boss has told me I can find a consulting contract I like and that he'll backdate it to when I began so I at least have proof for any future employers that I wasn't unemployed all this time.
Any advice would be greatly appreciated!
<bot>: Boss persuaded me to invoice him and not pay tax for 4 months, now I'm worried I'll be screwed in the future because of it.