Annuities are entered in the Pensions > Annuity screen. In this screen there is a choice of 'pension', or 'non-pension' annuity. A key distinction, here, is that the software assumes - automatically - that a 'pension' annuity is necessarily a 'lifetime' annuity and, as such, this will only end at death. Therefore with a 'pension' annuity you can not select an 'end' event.
As a result, to enter a fixed term annuity the first step will be to select the 'non-pension' option - a 'non-pension' annuity is assumed to be a Purchased Life Annuity (PLA).
When you select this option, you'll then see the further choice of 'lifetime - yes or no?'. Select 'no - with 2 further things to note:
1. The software will now be asking that you specify a 'capital element' (because it's a PLA). If it is a PLA, enter the capital element, if not, it will be necessary to enter a nominal value (e.g. 1GBP), and this amount (which will form part of the total 'payment', received by the client) will be treated as a 'return of capital' and, therefore, not subject to income tax. The rest of the payment, of course, will be subject to income tax.
2. If you scroll down, you'll now see that there is a 'Term' field, where you can enter the relevant term.