You will automatically be enrolled onto the 12 month route, with the opportunity to extend to the 18 month route.
If while you are studying at Aston you decide that you wish to do a six month placement you will have to make a second visa application.
Students are now not permitted to extend their visa while in the UK if the reason for an extension is to add a placement.
As the course will be extended to an 18 month course, you will have to apply for a Tier 4 visa extension to cover this extra period and you can now do this in the UK meaning that your studies do not need to be disrupted.
You will have to pay a second visa application fee when you apply for your visa, currently £457.
There will be an additional IHS fee, the cost will depend on when you apply for the visa. There may (not guaranteed) be a refund given for any time unspent on the previous visa.
Please contact the International Student Advice Team if you have any questions about how these placement years affect your Tier 4 visa application.