It looks very much like you registered and ordered a SIM card at the same time.
Its the weekend, so dont expect any change to the current situation until this coming Monday.
Smarty will send you a SIM card by first class post, which you should receive by Tuesday or Wednesday. When you receive the SIM card, you will be able to choose the activation date of your plan, so dont worry / think that you have wasted the £20, because you have not, as the first month is paid for in advance.
Your new Smarty number will probably appear online in your Smarty dashboard and the Smarty spp sometime after 12 PM midday during this coming Monday.
The above process is what I myself went through last week when I joined Smarty.
Sit tight and everything should be fine early next week.
The SIM that you currently have in your mifi is not registered with Smarty, so wont pick up a signal or access the network.
