Self employment and 2 months marking contract

[modshoraj]

Please can someone guide me please.

For my self employment business, i am paid cash and atimes i gather all the money together and deposit it once in bulk in the bank but i have invoices to support the money for each customer.
For ex,cust a pays 150pounds,customer b pays 200 pounds and customer c pays 100 pounds and i deposit the money in bulk in the bank(450pounds).I have invoices for each of the customer,although i deposit the money after the dates on the invoices.
Can i use my bank statement and invoice to proof this earning.

Secondly,i do mark scripts and i get paid by cheque and bank transfer.I am sent the remittance advice that states the gross and net pay in to my account and this can be matched with my banks statement.
its a contract job for 2 months.is it the gross or the net pay that i can claim for earning.
The document i have to proof the earning is theremittance advice that states the gross and net pay after tax and the bank statement where the cheque is paid in / money transferred to my account(BACS).Can i use thsi combination.
tHANK YOU for your help.I hope i have not bored you with my long story.