www.lhr-lgw.co.uk and check the dates and flight numbers. Logs are 100% coverage and 99% accurate too these days but don't know how far back this goes.
As far types based, they have had 757 and A320s and A300s at Gatwick for years, expanded to include the A321, B767-300 and off course the A330. All these can be seen on a sunny morning at Gatwick. Hope that helps a bit.