You should still be able to get access to the freesat home transponder and quite a few channels also transmitted from the wide beam transponder at 28.5E (Eutelsat28a) so no reason to disconnect your lnb cables.
See
http://en.kingofsat.net/freqs.php?&sat=57&standard=All&ordre=freq&filtre=Clear
Your box should still work with these channels and have a full epg. You can’t of course record any new content from channels you can no longer receive.
If you install the Custom Firmware after adding all the free channels from 28.5E you should be able to set manual recording timers for all the channels that aren’t on the freesat epg while remaining in Freesat mode using the CF Channel Editor package. .
I can’t see any reason why you won’t be able to watch any existing recordings.
If you have any older CH4-HD recordings despite not being able to view live these should replay OK. Same for any recordings of channels you may have lost since transfer to Astra 2F
list here
http://en.kingofsat.net/freqs.php?&sat=149&standard=All&ordre=freq&filtre=Clear