The RT practical takes the form of a flight from A to B with various events along the way.
If you've handled the radio on your Nav's without too much problem then the RT practical shouldn't be too taxing. Position fixes, relayed maydays etc are all part of the fun so ensure that you're up to speed on these.
I wouldn't pay for any extra tuition or courses. Your instructor or school probably have a couple of 'mock' practicals for you to experience - that along with CAP413 / Thoms APM / or AFE notes should give you all the examples that you need. I know the APM has a number of example flights in so I'm guessing the others do (sorry, no experience of them!)
As for Basic / FIS - again, I wouldn't worry. You're examiner will be able to cope with whatever you ask for. Discuss what (s)he's expecting with him/her in the preliminaries.
Best of...
DD