This is what I bought to try in the end...

Daler Rowney
Langton Watercolour Pads HP (Hot Pressed)
12 sheets 300gsm Watercolour paper.
– 355x254mm (14x10in) Code 403 401 410

The woman in the shop said it was pretty much the same as Arches. I've found a place locally that does the Arches Hot Pressed. Will try the two for comparison, the Daler stuff works out quite less expensive.