If you succeed in your application to easyJet and you have an ATPL, you WILL go straight in as a Senior First Officer.
As you've got no experience on heavier types, your only way into the company is via the TRSS scheme. You will earn less money than a direct entry pilot joining the company with a type rating or more relevant experience, but you will be on a higher payscale then the 2-stripe F/O's.