Jet2's plans seem to be changing by the minute. According to the 'Jet2' thread 2 757 and 2 737 are to be based, alongside 146 for the LGW runs. However, last plans were for 1 757 and 3 737, which is not actually enough for the current schedule.
Take a monday for example:
A/C 1 - 0640/0945 LGW
1015/1315 LGW
A/C 2 - 1010/1635 KRK
A/C 3 - 1030/1710 PMI
A/C 4 - 1255/1935 MJV
Still leaves PSA 1030/1710, ORK 1630/1930 - so maybe 5 based aircraft is happening, with the addition of 146 for the new LGW route?