It is not possible to pay at the pump with Monese card, you can use the Monese Card to pay for the petrol by taking it to the cashier.
There are also some airlines which do not accept debit card payments in-air so be sure to withdraw some cash if you need to spend money mid-air.
There are also a number of merchants that Monese will not allow to be processed and such merchants may be blocked if they fall into certain categories. These include:
Dating and Escort Services including advertising services
Automated Fuel Dispensers
Quasi Cash Services
POI Funding Transactions
And finally, some on-line merchants require 3D secure (MasterCard SecureCode) and this program is not yet enabled on Monese cards. We are working on it and expect it to be available in Q3 2017.