When I did a lot of backpacking (in my younger days
) I restricted my load to 40Lbs. I know the army lads regularly carry twice that but, for me, that was the maximum for me to still enjoy what I was doing. If you are going to carry that much make sure you have a decent rucksack with a hip belt that allows the load to be carried on your hip. Be realistic about the distance you travel each day; ten or twelve miles may even be too much to start with. Only take what you need as Wayne says; you won't need an axe for example as you won't be lighting fires I suspect.
Remember, April in the Lake District can be pretty cold so your kit will need to include good layering to allow you to trek and carry your load without overheating but stay warm when you stop and in the evening. Staying dry will be essential as well.
Just a thought, but why not try a short trek more locally first? - a weekend doing a ten mile hike on the Saturday for example.
Cheers,
Broch