Setup Cisco 800 series for ISP /31 and 8-block

Hi

I have made a bit of a school boy error.
I have had a leased line put into my house, to save £70 pcm (Yes they charge another £840 a year for   managed router) I have opted to go “wires only”, thinking how difficult can it be?
 
 So with a Cisco 897VA under my arm (it has WAN side SFP which I need) I set about making it work.
 
 But,
 
My ISP has given me
 
WAN side
a.b.c.1/31
with
GW                        a.b.c.1
My side                  a.b.c.2
 
And my /29 as a routed subnet..
 
 So I have
x.y.z.1/29
with
x.y.z.2                   My Cisco and GW for other 5 usable IP addresses.
x.y.z.3-7               My usable IPs in the 8block for LAN routers etc
x.y.z.8                   Broadcast for the Subnet.
 
Ok, HOW THE HELL do I set that up?
I assume I want NAT as other wise I don’t see how the x.y.z traffic will find it way up the a.b.c hole but if I use normal NAT my x.y.z subnet isn’t exposed as “external ips”
As you may have guessed, I have only dealt with 8block on serviced router scenario, which seemed very simply.
If anyone could give me child’s lesson in getting my 897 to present 5ports as my 8block and use the SFP as my WAN link that would be great, I can currently get it to kinda work but the ports aren't "open" to the internet on the 8block.
 
 I am sure I have missed something stupid, but I guess that why I generally don’t do this part…
 
Thank you… 😊