Yep, Zap-Map is the goto app for me, especially for longer distance and motorway drives. But if you want to save a few dollars get the Pod Point app and filter on 43-50kw chargers - you'll get a mix of Tesco and Lidl locations and they are the cheapest on the road (that aren't free) - currently 40p/kwh. They're not super quick but you'd usually be looking at 66p/kwh at motorway locations. Some are reasonably close to motorways (Waltham Abbey, Camberley etc on your route) - depends how much of a rush you're in. Just watch out for Lidl's that have ANPR car parks and make sure you abide by the rules (potentially buy something instore).
I've driven over 14,000 miles since March in my 5LR with 2 kids (2 and 5) and charging while out an about on long drives is no worries.. getting kids out of a car, past the service station kids ride and to a toilet and back takes an easy 30 mins and time for a decent top up