I would order afternoon tea for one person and just a tea (beverage) for the other because afternoon teas are usually impossible to finish unless you gorge yourself and feel unwell afterwards.
My local (nice) hotel does afternoon tea for £12 and for that you get two thin sandwiches cut into triangles, one large scone with jam and cream, a portion of meringue, a small portion of cheesecake, portion of chocolate torte, and fairy cakes.
I find that is just right for *two* people rather than one, so it comes in at £6 each.
Tea isn't meant to be a filling meal - it's a treat and a frivolity.
If I ate all the above (as proposed by the hotel) it would be too much.