My current employer has a three month notice period, but I didn’t sign the contract, I did however take payment. How legal is this and can I just use the standard one month period?

Cheers

If it was public knowledge and like that when you joined the company you are probably deemed to have agreed.

However if you leave after one month there is little the company can do – they can sue for breach of contract but will only get whatever losses they can prove

They can only enforce the statutory minimum, which I presume your length of service means is one month?

I wouldn’t expect they could sue you for breach of contract if there is no physical signed contract as proof!