Welcome to the forum
.
Of course you can navigate the application yourself... most people do. It's pretty straightforward - you just fill in the application form and provide all the documents listed on the application form.
You just need to make sure:
1) Your relationship is still subsisting
2) You still meet the financial requirement (you can combine your income with your spouse's to meet it if you need to).
3) You still have somewhere suitable to live
4) You have proof that you have lived together for the last 2 years (by way of 6 official documents in each of your names addressed to you at the same address, spread evenly over the 2 years - this is all described in detail on the FLR(M) form.
The only reason you might need professional help with the application is if you have serious, real reasons why you feel you might be refused, such as previous criminal convictions or illegal immigration history in the UK.