I have done this several times in the last few years. I took my DN when she was 6yo and she loved it- it took us about 2 1/2 to 3 hours cause she and her mom eat slow, and DN got the Strawberries with whipped cream for desert, BIG bowl of food!
And I took my brother last time- we both got the Grand Tea, and when the CM found out he did not like sparkling wine she said they had port, WOW! it was great! He hates, hates, hates any thing with mayo in it and still liked all the sandwiches.
I was there having tea alone a few trips ago and noticed a small group of teenage boys having tea, thought they might be from the UK, but they wern't- I asked them. They just thought it looked good, the pastries, the strawberries and so on, so they did "Tea". The were around 15 to 17 yo, I only noticed cause my DS is around that age, and I had never thought to take him, even thou he will try any thing food wise.
I hope to go in Sept for my B'day. It might be a solo trip, but this is such a great place I won't mind. And if not we have a trip in early Oct that has gone from 6 of us going to about 12 to 15 now.. won't know till Sept. We had to get two 3 bedroom places for us all, so if we decide to do Tea I will need to call asap! Hope they end up extending the Fireworks Desert Buffet at MK by then!