Can you give us a bit more about the area and type of accomodation you are looking for, before I bore you with lts of useless stuff.

and which part of Canada you fancy going to, and where in the Uk you would want to ideally fly from.

Air India do a regular direct flight from Birmingham to Toronto. I've used it and it is very good.

April is a good time to drive. I used to drive from seattle to Canada around Nov so scarely, waxy ice and a lot of car slip out of road.
not much details for the trip, hotel reservation you may try and select by yourself;

abahotelscom

There are not much information but fair price.

It depends where you want to go. We flew to Calgary from Manchester in June 2005 and did a self drive tour of the Rockies. We booked the flights and car hire through Canadian Affair and found the accommodation ourselves, staying various places between Banff and Jasper. The scenery was spectacular and we saw lots of wildlife. In April I think it could still be pretty snowy in the Rockies though. If you are interested in that area I can give you more info but have a look at http://www.canadianaffair.com/ for some ideas.