My employer said they would pay me in lieu of notice, can they do this?
Unless there is a clause in your employment contract which states that the Employer can pay in lieu of notice then the Employer would be in breach of contract by doing so.
However, your remedy for breach of contract is compensation that puts you into the position you would have been had the Employer not breached your contract. Therefore as long as your Employer pays you your normal salary for your full notice period then there is no real benefit of pursuing a breach of contract claim.
The exception to this is where you are paid for the work that you do, or your pay is linked to actually doing work. For example you are paid commission and you are unable to earn the same amount because you were not given the chance to work your notice. The value of your compensation would be the difference between what the Employer paid you and what you would have earned if you were still at work.
If you are in any doubt about your rights you should seek some advice.