Something I haven’t seen mentioned yet, the reason you were unable to warp out is likely due to warp disrupting frigates that frequently appear in level 4 missions.
They are small and fast, so it’s hard to kill them with big weapons and they love to eat drones. However, since they love drones so much, you can use that to possibly get away.
Drop your drones out. Select a station on your overview (or planet if there’s no stations). Select the “Align to” option so your ship starts moving towards it, and repeatedly try to warp to the station until the frigates get distracted by your drones long enough for you to leave.
But yeah, level 4 missions are a big jump from level 3. It’s typically recommended to continue doing level 3 missions until you’ve got a solid skill base. (all the gun/missile support skills to at least 3, preferably 4, and the ability to fit all T2 modules for your tank.) Also you will need a way to deal with the frigates. target painter + stasis webifier can work well for that. Light combat drones can also work, but the warp disrupting frigates kill them very quickly.