I'm in the UK too, that protein powder sounds quite good (I wouldn't be able to have it due to the oats though).
My husband orders Pea protein and organic rice protein powders from Iherb, they have cheap shipping and low prices (you just have to make sure you stay under the customs charge threshold otherwise your order ends up at the post office for days and you have a customs charge to pay!).
I'm not sure how primal pea and rice protein are considered to be, but we find them quite digestible. I'm not keen on the taste of pea protein though, it is a bit savoury (kind of like lentil soup!). Rice protein is bland so mixes with anything, but has a bit of a chalky texture.
Good luck! If you do go for the pea protein, I find mixing it with cinamon improves the taste. The Maca will probably improve the taste too, Maca has a kind of malted "horlicks" type taste.