You are correct, according to the ESM (Electronic Service Manual aka DVD) it is every 25k miles
It's not a difficult job ......
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Special Tools Required
Tappet adjust wrench set
07MAA-PR70100
NOTE: Adjust the valves only when the cylinder head temperature is less than 38 °C (100 °F).
1. Remove the cylinder head cover.
2. Set the No. 1 piston at top dead center (TDC). The punch mark (A) on the variable valve timing control (VTC) actuator and the punch mark (B ) on the exhaust camshaft sprocket should be at the top. Align the TDC marks (C) on the VTC actuator and exhaust camshaft sprocket.
3. Select the correct thickness feeler gauge for the valves you're going to check.
Valve Clearance
K20Z2 Engine:
Intake:
0.21−0.25 mm (0.008−0.010 in.)
Exhaust:
0.28−0.32 mm (0.011−0.013 in.)
K24A3 Engine:
Intake:
0.21−0.25 mm (0.008−0.010 in.)
Exhaust:
0.25−0.29 mm (0.010−0.011 in.)
4. Insert the feeler gauge (A) between the adjusting screw ( B) and the end of the valve stem and slide it back and forth; you should feel a slight amount of drag.
5. If you feel too much or too little drag, loosen the locknut with the special tools, and turn the adjusting screw until the drag on the feeler gauge is correct.
6. Tighten the locknut to the specified torque and recheck the clearance. Repeat the adjustment if necessary.
Specified Torque
K20Z2 Engine:
Intake:
20 N·m (2.0 kgf·m, 14 lbf·ft)
Exhaust:
14 N·m (1.4 kgf·m, 10 lbf·ft)
K24A3 Engine:
20 N·m (2.0 kgf·m, 14 lbf·ft)
7. Rotate the crankshaft 180 ° clockwise (camshaft pulley turns 90 °).
8. Check and, if necessary, adjust the valve clearance on No. 3 cylinder.
9. Rotate the crankshaft 180 ° clockwise (camshaft pulley turns 90 °).
10. Check and, if necessary, adjust the valve clearance on No. 4 cylinder.
11. Rotate the crankshaft 180 ° clockwise (camshaft pulley turns 90 °).
12. Check and, if necessary, adjust the valve clearance on No. 2 cylinder.
13. Install the cylinder head cover.
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I've just remembered, member hughezee does Honda's and he's in Staffs (Burton-on-Trent)
http://typeaccord.co.uk/forum/user/2850-hughezee/
he was last on here on 7th Feb
http://typeaccord.co.uk/forum/topic/23017-2000-main-relay-issue/?p=238591 so he's still going
his website
http://www.hondaman.co.uk/faq/4590911678
he's your best bet, apols to you and him that it took me so long to remember