You won't qualify for letting relief unless the property has been your main residence at some point during your ownership.
A married couple can only have one main residence between them so transferring the property to your wife won't work.
The only way to avoid CGT, but not necessarily altogether as that would depend on the facts and figures, would be to move into the property for a period of time before you sell it. There is no set period and you will read on some websites that a few days or months is sufficient time to qualify for the last three years of ownership relief. However, I would say that you need to live in it for a year at least and even then the tax office may question your motivation for moving into it with a view to disallowing the claim for main residence and letting relief on the basis that you had no intention of making the property your home and that you moved into it simply to try to avoid tax. You would need to show that you had moved your "life" to that property, if asked.
You could minimise the potential CGT liability by putting the property into joint names which will at least give you two CGT exemptions of £10,900. In addition, if you did live in the property and claimed main residence relief, you would also qualify for two lots of letting relief subject to HMRC not querying it.
There is, of course, no guarantee that the tax office would query a claim for main residence relief but the shorter the period of occupation the greater the chance that questions will be asked.
Take a look at HS283
for more information.
I hope this helps but let me know if you have any further questions.