Adjustable Height Desk - Needed for Charity Work and more! (Ashurst Wood RH19)

Hello

I am after an adjustable height desk so that when conducting various charity work volunteers are able to stand and not be sat for hours on end. It is likely I will mostly be using this and as I have a bad back from my time in the army I thought this would help me put in the extra hours needed for all the volunteer work I do.

I work for the Sea Cadets and I run a support group for mental health aimed at mainly veterans.

So please if you have a desk that can go up and down or even if it is fixed at certain height so work on computer can be done at a standing position it would be a great help.