Can you narrow it down to a county as some places are easier to get to than others in the NW - how far are you prepared to travel and when in the season were you aiming for?
SE and sw are probably outside of travelling range but other wise anywhere in England, perth is as far north as i would like to travel... As to when I think I am ready for something very straightforward ...
If you are able to travel over to Yorkshire, Richmond (May) is a lovely first event. Quite straightforward with nothing too scary, hills aren't too steep either.
Hexham is lovely flowing course but some steep sections that may tire anything other than a very fit horse. Jumps don't seem to be up to height so good for novices.
I wouldn't advise Hutton as a first event (June) as it can be quite technical and feels like a long course, need a very accurate rider and obedient horse that stays on its line.
I loved Hopetoun last year, jumps were quite plain, nothing too fancy and the old turf felt lovely to ride on, great atmosphere aswell.
Cumwhinton is a straightforward course but has life size llamas that can spook some horses. Feels like jumping from one field to the other rather than a traditional course, but well organised.
I didn't get down to Cheshire last year but I understand there are a couple of courses that may suit.