Hi, I have just setup my Draytek 2860 and AP-900.

Should I use the same SSID ? My laptop can pick both SSID;s up? will it cause an issue, i want it to be able to switch access point and use the closest one.

Use the same SSID, username & pass ...
about using the same channel is depending the wifi network > some claiming needs different because the network cards of the devices (laptop,mobile etc) are "lazy" to change to closest / nearest when both access points (2860 & ap 900) if all wireless access points using / have same channel ... can use the 1 and 6 or 11 ... but then with some cases they may overlapping if are set to the same channels
There is a program called inSSIDer which will show the free & possible overlapping channels to see what is best for your network

Also for a device to change the channels more easy (to the stronger signal) you may need to set the roaming aggressiveness of the network interface card of the device if is possible to higher settings

thanks for that ill give that a try and post results