pop into the A-Z & take a look at the Acer section Kornos. You can see the colours & names (if given) of all the colour range.
I was at a garden centre yesterday & some of the acer's still have colour on them so that can give you an idea of what their potential is. They should be reducing the price's now as a bare pot of twigs is'nt so appealing, that's when I make my move btw ;-))
As for your existing tree's without a photo it's hard to know what the situation is. They are pretty much going dormant now so no liquid feeding until next Spring but you can carefully remove the topsoil around the plant & topdress with fresh soil/compost with a handful of slow release fertiliser. My favourite is BFB (blood/fish/bone).
Depending how far you want to go is the soil-testing kit to see if your soil type is compatable with the plants you want to grow well.
Last point is acer's do so much better when sheltered from burning sun & burning wind, like me they prefer dappled shade :-)
Google 'Acer Nurseries' if you want to find a specific tree. Good luck.

Try Acer palmatum 'Osakazuki' for good orange/reds, and A. palmatum 'Crimson Queen', which is a dark red cut leafed type, always produces good colour for me. The best ones however are the more palmate types, green leafed, rather than the cut-leafed ones, because of the contrasts in the leaf tones. Phil J

Thanks Phil
I'll make a note of the Acers you have mentioned-there are some beautiful trees out there this year.
best wishes and thanks.

My Acer Palmatum Dissectum "Osakasuki" has been a fantastic vivid red for a few weeks now and is just beginning to lose its leaves . The most stunning of reds.

In fact , a very attractive tree throughout the year too, even before it changes to red in the autumn

I recommend it

Dear Inverglen
Many thanks for the name of the Acer-I'm making a note of it now-trouble is a lot of the nurseries don't stock anything 'unusual' but I'll have a try to find one
Thanks