The ECO needs to be convinced that a marriage/civil partnership in the UK will take place.
The law relating to marriage in England and Wales does not allow for any arrangements to be made with a Registrar until the foreign national has arrived in the UK. Of itself, a booking at a Register Office or church is not proof that a marriage will take place.
However the ECO can reasonably expect the couple to have made some tentative plans for the wedding. Any evidence at all, however small, that's available to show that wedding arrangements are in hand will help in this respect.
Think about including any facebook messages, e-mails or texts that specifically refer to wedding plans. The engagement ring receipt is a good. Even a supporting letter from your fiances parents saying that they support the future marriage and that they are looking forward to meeting and welcoming you into the family. Nothing complicated.


Regarding your English language ability - see the English language page
My personal advice would be to organise the test and submit the pass certificate. It's the easiest and safest way.


The UKBA require statements covering at least 3 months, and clearly demonstrating that there is adequate amounts. They will not accept statements/letters etc that simply show the balance in on a particular day, as these documents do not show that there are consistent funds to meet the maintenance requirement.
The maintenance test will, in most cases, be based on the sponsor's income/employment

If your circumstances are straightforward there is really no need to hire a solicitor.
If your case is complicated then the experience of a good immigration advisor would help.

Don't forget that you and your fiance will still need to supply all documents/letters and information required yourselves, the solicitor cannot do that.

Have your fiance write a good letter to the Embassy supporting your application, and outlining how long you have been together and important events and meetings between yourselves.
You may also briefly outline the start of the relationship, how it developed, the times you met face-to-face, some things you did together, your feelings for each other, why you want to marry, plans for the future and where you will live and how you will support yourselves.
Keep it simple and above all be honest about everything.

Hope this helps