Property purchased with tenant

Other

We have purchased a property with a tenant on an assured shorthold agreement - this is due to expire on the 29 th of April 2008. We are looking to give the current tenant both notice to quit and notice that his rent will increase. Just incase he is not happy to pay the increased rent and we need him to leave.
Ob. the agreement is between him and the old owner. I was looking to issue the standard notice but what details do I put on it ?
Or is the old agreement void now we own it
thanks for your time