If you really want to do the job properly and let the coppice grow back so it can be used for thatching spars and hurdles after a rotation or 2, you need to make sure that deer really can't get in.
There are several ways to do this. The most comprehensive, which should prevent deer, rabbits, hares and people(to some extent) getting in is metal deer fence with rabbit mesh at the bottom using good strainers at corners and changes of direction and posts in between. This is really more permenant deer fencing and is quite expensive even if you do it yourself, which is quite heavy work.
If you use plastic net, you may find the cheapest supplier is your local agricultural wholesaler. Some do their own make. The best, but often most expensive is Tenax. If several people get together there is a bit of a reduction for over 10 rolls I understand. If plastic mesh is hung from wires stretched between good strainers and posts with rabbit mesh at the bottom, it will last for years, but is prone to vandalism.
I have often seen plastic mesh hung between long hazel props, and quite honestly, if you want a crop from your hazel, you are wasting your time with this, as the mesh sags and deer and rabbits can get in quite easily. This is, however the cheapest option.
If you have a fair number of rabbits make sure you use rabbit mesh at the bottom. They can decimate coppice in large numbers. Of course make sure you are not enclosing a warren. You will probably find there is someone round your way that will catch rabbits for you if they are a major problem.
You could also consider crowd control fencing.
Sorry if this answer is a bit over the top, but there is really no such thing as good cheap fencing.
If you are restoring coppice you may be able to get a grant towards the costs from the FC, which I assume is what you are doing as temporary deer fencing is a requirement. The grant available should go a long way towards paying for the materials, but will not really cover labour.
Chris W