I love this site, this is the same question I was wondering. I haven't had mine yet today and am not particularly hungry so I could do with this answer too
A: It won't affect your weight loss if you don't take all your Healthy Extra choices. However, the Healthy Extra section is there to ensure a balanced diet, so from a health point of view we recommend that you enjoy all your Healthy Extras each day.
Q: Can I mix and match my Healthy Extras by halving the portions?
A: Yes, if you like - you'll still lose weight beautifully! The downside is your speed and fibre symbols would have to be ignored unless your two halves had identical symbols. However, mixing and matching couldn't be done when there are multiple items in one choice, e.g. 28g Kellogg's All-Bran 1 Ryvita Multigrain crispbread. With all single item choices, feel free!