for your £300.00 you get your Inspection 2 service & the oil service after that.
The Inspection 2 service alone is worth just over £300 anyway so your making the saving of the oil service which is around £125.00.
So really the answer to your question depends on yourself......
How long will you be keeping your MINI?
When you do come to sell it... Do you want to keep the re-sale value higher by having a service package on it?
If I were in the situation that my TLC was running out.... I'd buy the XL pack.
Hope this helps,