I assume its the assets based at Mildenhall but given the location, I assume they are parachuting into the sea? Depending on the time and how far out they are you may or may not see anything at all but thought it worth a heads up.
H3015/18: Parachute jumping will take place
Q) EGTT/QWPLW/IV/M/W/000/040/5159N00125E005
MIL EXER. MIL PARACHUTING AND NIGHT WATER HOIST WI 5NM RADIUS
515900N 0012500E (BAWDSEY, SUFFOLK). FOR INFO 01638 545012.
2018-05-0624/AS3
LOWER: Surface, UPPER: 4,000 Feet AMSL
FROM: 30 May 2018 18:45 GMT (19:45 BST) TO: 30 May 2018 21:30 GMT (22:30 BST)