From my days (NB Gnat - a real aeroplane
) 2000 ft would PROBABLY be flat, but depending of the nature of the cloud a roller might have been possible, eg broken, etc. Nothing to stop the team entering cloud - we sometimes did, but the crowd need to see it and if it gets bumpy inside it also gets quite exciting. I recall looping into the base of a CB at Baden-Soellingen and one wingman 'took some leave' and rejoined us later.
The team will always be flexible and the show can go from a 'flattie' to a 'fullie' or 'roller' and back again as the leader and synchro determine.
Hope you get a good show. North east of BOH in Sussex right now you would PROBABLY get a 'fullie', but if the 4/8 is in the wrong place at the wrong time...................... and it will be hard work for the team with this airmass.