This particular variety is grown more for its striped appearance than its seed heads - they don't always flower, and only if they do will you get seed heads.

Yes, some Miscanthus varieties produce their flowers too late or don't even emerge in time before the frost hits them. All parts of the UK are just a bit too far north (Even Cornwall) to have a long enough season to get them to flower.

You are best selecting forms that produce their flowers earlier (by at least a month). I have Miscanthus sinensis 'Yakujima Dwarf' and M. s. 'Ferner Osten' which are great. There are many other named forms that flower well.

A member on here called Bluespruce uses a lot of varieties in his conifer garden/nursery. Contact him for what he considers the best.