Budget afternoon tea and timing

I’ll be in London in April with family and we’d like to have afternoon tea.

We had one only once in the past, at The Wesley and it was fairly cheap compared to a lot of other places, around 15£ per person.
The location wasn’t particularly quaint, but food was good and we were happy with it.
So I’m considering going there again, but for the sake of making new experiences: are there similar priced afternoon teas you would recommend?
I found Huffkins (with Groupon)in Oxford Street and Pembroke Primrose Hill in Camden.

Has anyone been there?

Another thing is the time. It seems like Huffkins on Saturday lets you reserve no later than 12:00, The Wesley no later than 13:30 .is this normal that on a Saturday afternoon tea equals lunch?